When I removed the stock style shackles the rust was imbeded into the rubber. I do not even think the shackle could rotate during the flex. NOT GOOD.

If you had greasable shackles maybe get away with. But sounds like you will be doing a remove and grease. It will keep the rust at bay and help with flex/rotation. I would also consider drilling the bolts, installing zerc / grease fitting so you can add grease as PM, use lithium or similar so does not rot the polly bushings.